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Abstract

One of the phenomena limiting the performance of pulse detonation engines (PDEs) is detonation failure due
to pulse-to-pulse interference. To better understand and control such interferences, two novel laser diagnostic
techniques, based on absorption spectroscopy, have been developed and then used to demonstrate effective realtime
control. The rst technique utilizes a tunable diode-laser (TDL) sensor to measure H2O temperature and
concentration in the tube tail end at the Naval Postgraduate School’s (NPS) PDE facility and in the tube head end
at Stanford University’s (SU) PDE facility. This sensor, capable of measuring temperatures from 300 to 1300 K
at 3.33 kHz, reveals the temporal history of temperature for multipulse engines. In its application to the NPS
facility, the sensor shows a distinct change in temperature pro le when the engine pulse rate is changed from 5 Hz,
where successful detonations are achieved, to 7 Hz, where interference produces undesirable ame holding and
subsequent de agrations on some pulses.We observed that the geometry evaluated possessed excess recirculation
at the higher pulse rates resulting in ame holding at or near the point of injection. In its application to the SU
PDE, this sensor reveals a temperature pro le characteristic of detonation failure that could be used in future
control schemes. The second diagnostic technique developed is used to monitor fuel and is employed in an active,
real-time control scheme. For this sensor, we monitor the C2H4 (ethylene) concentration at the tail end of the NPS
PDE initiator tube, which is operating at 20 Hz. When fuel is detected at the tail end, the sensor sends a signal
to re the ignitor. Compared to xed-timing ignitor actuation, this control promotes more consistent detonation
initiation and reduces mis re events. These two new laser diagnostic techniques provide useful tools for studying
pulse-to-pulse interference and lay the groundwork for future,more advanced TDL-based PDE control strategies.

The design and use of two-color tunable diode laser (TDL) absorption sensors for measurements of temperature and H2O in a rotating detonation engine (RDE) are presented. Both sensors used rst-harmonic-normalized ...

One method of solving the problem of burning or combustion at supersonic speed is by combusting in a stationary
detonation wave. Stabilization of a detonation wave has been recently accomplished and is reproducible, but ...

This paper presents the design and the experimental result of the active position control of a shape memory alloy (SMA) wire actuated composite beam. The composite beam has a honeycomb structure with SMA wires embedded in ...